There have been made various attempts to carry an inorganic compound, such as zeolite and aluminosilica gel, on a hydrophilic macromolecular substrate, such as cellulose substrate (e.g. paper), to impart various functions. Such attempts conventionally include coating and addition during paper making process. According to these prior art techniques, however, the above-mentioned inorganic compound, which is generally called a filler, is merely held on the surface of a substrate, or when the substrate is paper, in gaps between fiber and fiber, by the action of an adhesive, yield improving agents, binder and the like.
As a consequence, these methods are associated with a limitation on the amount of the filler to be held, and with marked inhibition of desired ion exchange capability and adsorbability, despite the desire to utilize the function of porous material such as zeolite, since the adhesive, yield improving agents, binder and the like block fine pores present on the surface of zeolite and the like.
When paper is manufactured by these methods, the filler coagulates as a result of the action of the above-mentioned binder and the like, thereby clogging a paper making wire. Thus, the paper making process itself is difficult to complete. In addition, the resulting paper sometimes loses strength significantly, because the filler held on between fibers inhibits the hydrogen bonding between fibers.
To solve these problems in the paper making procedure, for example, a starting material of inorganic compound, such as aluminosilica gel, is added to the pulp to be manufactured into paper to allow reaction within the pulp, so that the resulting paper can have improved properties. For example, Japanese Patent Unexamined Publication No. 125694/1993 discloses a method comprising impregnating paper with an aqueous solution of an alkali metal salt of silicic acid (silicate) to allow contact with an acidic gas, thereby carrying the silicic acid, to manufacture an inorganic paper having optical property, adsorbability, oil absorbability and printability. Japanese Patent Unexamined Publication No. 106199/1993 discloses a method comprising immersing fiber holding an inorganic silicon compound, in an aqueous solution of aluminate, and immersing same in an aqueous solution containing at least one member selected from water-soluble salts of copper, silver and zinc, to afford antibacterial property, deodorizing property and adsorbability of the fiber.
These inorganic paper and fiber nevertheless show poor adsorption of the ion of transition metal such as silver and copper, and the metal-substituted silicic acid-carrying inorganic paper and metal-substituted aluminosilica gel fiber show poor deodorizing property. Therefore, a carrier taking the place of the silicic acid and aluminosilica gel has been desired.
In other words, inorganic porous crystals, such as zeolite and hydrotalcite capable of holding metal and the like better than aluminosilica gel and the like, are desired to be held in the inner matrix of hydrophilic macromolecular substrate such as cellulose.